I know a guy who had a 27 spline. It was locked & on 33s. He said he was not easy on it.

 

for 33s and a 4.0L id just regear and carry spare shafts, and put 760 ujoints in the front with full circle clips.

and you might as well throw in some lunchbox lockers

for peace of mind you could do and 8.8 swap (33 spline shafts, availible in 3.55/ 4.10 from the factory and LSD's and same wheel pattern as the xj) all it really requires is new spring perches and shock tabs

 

I beat my dana 30 and 29 spline 8.25 with Lockers. Put sleeves and c gussets on the 30, but didn't have any issues with it before the sleeves and gussets. I run 35s and 4.56 gears. I carry spare front axle shafts, but the only one I've broken was caused by the clip falling out and the cap popping out.

 

I have a 96 Cherokee, im pretty sure i have 27 spline 8.25 in the rear. Would i be okay rock crawling with a locked 8.25 in the rear and D30 up front? How solid is my setup as it is?

 

You could have a 27 or 29 spline 8.25, if it's a 27 I wouldn't go bigger than 33s and 35s if it is a 29 spline.

 

I have a 96 with D30 and 8.25 both have lunch box lockers and 33's. I have never had a problem. And all my jeep buddies have 35's and bigger and I am able to keep up with them. Keep what you have and if it breaks then use all the info that everyone has given you and beef up those axles or go get 1 tons.